The provided image shows four chemical compounds: $(CH_3CO)_2O$ $(I)$, $CH_3COOH$ $(II)$, $PhOH$ $(III)$, and $CH_3COCHO$ $(IV)$. Identify the correct statement regarding these compounds.

• A
  Compound $I$ is an anhydride.
• B
  Compound $II$ is a phenol.
• C
  Compound $III$ is a carboxylic acid.
• D
  Compound $IV$ is an ester.